The pantothenic acid derivatives represented by the above general formula (I) were found out as compounds having an inhibitory effect on acyl CoA-cholesterol-acyltransferase (ACAT) (JP-A-3-218340; the term "JP-A" as used herein means an "unexamined published Japanese patent application"). It is known that ACAT is contained in a large amount in intracellular microsomes in the liver and small intestine and participates in the intestinal absorption of cholesterol and the accumulation of cholesterol ester in cells. Accordingly, it is expected that compounds capable of inhibiting ACAT are usable as drugs having a blood lipid-lowering effect as well as an antiarteriosclerotic effect.
It has been confirmed that the pantothenic acid derivatives represented by the above general formula (I) have excellent inhibitory effect on ACAT. When orally administered, however, these compounds are scarcely absorbed via the digestive tracts and thus fail to establish any satisfactory effects.
Therefore, it has been required to develop compositions whereby the absorbability of the pantothenic acid derivatives represented by the above general formula (I) in vivo can be elevated and thus the bioavailability thereof can be improved. It has been also required to prepare the thus produced compositions into preparations in which the active compounds contained therein can be stabilized and stored over a long period of time.